1. The Field of the Invention
The present invention relates generally to fiber optic communication. More specifically, the present invention relates to systems, apparatuses, and methods for coupling and aligning an optical fiber with a fiber optic device for optical signal communication.
2. The Relevant Technology
Fiber optic technology is increasingly employed in the binary transmission of data over communication networks. Networks employing fiber optic technology are (known as optical communications networks, and are typically characterized by high bandwidth and reliable, high-speed data transmission.
To communicate over an optical communications network using fiber optic technology, fiber optic components such as a fiber optic transceiver are used to send and receive optical data. Generally, a fiber optic transceiver can include one or more optical subassemblies (“OSA”), such as a transmitter optical subassembly (“TOSA”) for sending optical signals, and a receiver optical subassembly (“ROSA”) for receiving optical signals.
More particularly, the TOSA includes an active optical device that receives an electrical data signal and converts the electrical data signal into an optical data signal for transmission onto an optical network. The ROSA includes an active optical device that receives an optical data signal from the optical network and converts the received optical data signal to an electrical data signal for further use and/or processing. Both the ROSA and the TOSA include specific optical components for performing such functions.
In particular, a typical TOSA includes an optical transmitter such as a light emitting diode or a laser diode for transmitting an optical data signal to an optical fiber. A typical ROSA includes an optical receiver, such as a PIN photodiode or avalanche photodiode (“APD”) that receives the optical data signal from an optical fiber and converts the optical data signal to an electrical data signal.
A typical optical cable has an optical fiber of high refractive index surrounded by a low-index cladding. In order for an optical transmitter to transmit an optical signal to an optical fiber the optical transmission of the optical transmitter must be aligned with a viewing window of the optical fiber. Likewise, in order for an optical receiver to receive an optical signal from an optical fiber the optical fiber must be aligned with the receiving surface of the optical receiver.
Referring now to FIG. 1, a conventional molded-in optical fiber interface 10 is shown for passive alignment of an optical cable 20 with a laser 30. As shown in FIG. 1, the optical fiber interface 10 has an incorporated plastic cup 11 for receiving an optical cable 20, and an incorporated plastic base portion 12. The optical cable 20 comprises an optical fiber 21 of high refractive index surrounded by a low-index cladding 22. The laser 30 is incorporated into the optical fiber interface 10 opposite the optical fiber end-face 24 for transmission of an optical signal to the optical fiber 21.
Manufacture of the molded-in optical fiber interface 10 shown in FIG. 1 typically includes several manufacturing processes such as molding, die attach, and lead frame etching. These manufacturing processes must be carefully controlled because they contribute to the overall tolerance for alignment of the laser 30 with the end-face 24 of the optical fiber 21.
The optical transmission of the laser 30 may typically be about 8 micron wide when it leaves an emission cavity 31 of the laser 30, and project to about 50 micron wide when it reaches the end-face 24 of the optical fiber 21. Assuming a relatively large 200 micron diameter optical fiber 21, the manufacturer would be allowed a 75 micron overall tolerance for alignment. One of ordinary skill in the art would recognize that a 75 micron overall tolerance does not allow much room for error in the stackable tolerances of each of the several manufacturing processes required to manufacture the molded-in optical fiber interface 10. Equipment for obtaining these stackable manufacturing tolerances can be expensive. Holding the overall tolerance may still be difficult using this expensive equipment.
The molded-in optical fiber interface 10 is illustrated in FIG. 1 where the stackable manufacturing tolerances for the various manufacturing processes have not been met. As a result, the emission cavity 31 of the laser 30 is not aligned on axis with the end-face 24 of the optical fiber 21 resulting in at least a portion of an optical transmission from the emission cavity 31 of the laser 30 to fall outside of the end-face 24 of the optical fiber 21. This misalignment would likely result in a yield loss. The risk of losing the overall tolerance resulting in misalignment during the manufacturing processes further increases as the diameter of the optical fiber 21 becomes smaller, and also as the optical transmission of the laser 30 becomes more narrow and defined (e.g. a laser as compared to a LED).
Typically, in the case of a misaligned molded-in optical fiber interface the optical component incorporating the misaligned optical fiber interface must be discarded. Thus, the optical component along with any nonrecoverable components, for example at least the VCSEL and housing incorporating the molded-in optical fiber interface, would be wasted.
Therefore, in recognition of the foregoing, and other, problems in the art, apparatuses and methods for manufacturing the apparatuses are described allowing for more accurate and economic alignment of an active optical device with an optical fiber.